21876389 has 2 divisors, whose sum is σ = 21876390. Its totient is φ = 21876388.

The previous prime is 21876377. The next prime is 21876397. The reversal of 21876389 is 98367812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18105025 + 3771364 = 4255^2 + 1942^2 .

It is a cyclic number.

It is not a de Polignac number, because 21876389 - 2⁴ = 21876373 is a prime.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21876319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10938194 + 10938195.

It is an arithmetic number, because the mean of its divisors is an integer number (10938195).

Almost surely, 2^21876389 is an apocalyptic number.

It is an amenable number.

21876389 is a deficient number, since it is larger than the sum of its proper divisors (1).

21876389 is an equidigital number, since it uses as much as digits as its factorization.

21876389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 145152, while the sum is 44.

The square root of 21876389 is about 4677.2202214563. The cubic root of 21876389 is about 279.6781548577.

The spelling of 21876389 in words is "twenty-one million, eight hundred seventy-six thousand, three hundred eighty-nine".